Horse Power

I'm not dissputing that, I disputing your explination of it. It totally depends on the power curves. The most impotant factor in your example is average HP in the RPM range that you'll be using. The most average HP will get most work done. If you hit hill where both of those engine could hold a steady RPM at 500 HP, they would both reach the top at the same time. Once you lose RPM, the lower torque engine loses HP along with that torque.

No, gearing cannot change anything. It can increase torque by trading off speed, or increase speed by trading off torque. It can do nothing for horsepower.

What you need to do is stop separating the two and embrace their relationship. HP = Torque x RPM ÷ 5252. Don't push off math becasue it's "Not real world", it has everything to do with what you feel while driving. You just need to understand it so you have give good advice based on your real world experience. Plug some #'s in that simple formula and you'll see how less torque means less HP at any given RPM.

 

It's obivious you have more knowledge of how HP and torque are rated and the formulas for such. My original statement is based upon the idea the OP is looking at used fleet trucks to do a cetrain job. My premis is look at the torque rating as much or more than the HP ratings in these types of trucks. Many times a company may purchase 450-500hp trucks, but cut the torque down in order to use cheaper drivelines, hurting hill pulling power.

In my experience, lower HP engines are affected more by as little as 100 ft lb of torque difference than a 600+hp engine. 400hp and 1350 torque with 3.55 or higher rears is a miserable experience in the hills, where the same specs with 1550 torque is much more enjoyable. Been there and done that.

 

HP does not pull a load up a hill or down the road, torque is what gets the load down the road. But it does take HP to make torque, and take torque to make HP. someone saying there motor is turned up to 600 or 700 HP means nothing unless your on a dyno, how often have you run down the raod pulling 1800 to 2100 RPM's because thats where your big HP and TQ is.

 

1 HP is the ability to do 33,000 ft-bs of work in one minute. Your explanation is all over the place, HP is torque, so it makes no sense to say that HP does not pull a load. 1800-2000 is not where your big HP and torque is. It is where the peak HP will be, but peak torque will be closer to 1200. Torque is nothing more than a force, it does not say how much work can be done in a timeframe. HP takes it further and tells how much work can be done in a certain amount of time. In other words, HP pulls loads up hills and down the road.

 

well then i guess all the big race engine builders have been wrong for years as they will give up 50 hp for 100 lbs of TQ all day long.

 

No they've been doing it right, you are wrong, not them. They build for the highest average HP in the the rpm range that they use in a race. No successful engine race engine builder builds for high torque #'s. The old saying among us drag racers is "build HP and the torque will be there through gearing". That was true 50 years ago and still true today. I will absolutely trade off peak HP for more average HP any day, but I will never build for torque. Torque can be gained with gearing, HP says it all. No matter how you slice it, more HP will make more torque for any given wheel speed. It is a proven fact.

Torque curves are very important in race engine building, but we don't see them as you see them. We see them more as BSFC curves to give us trends to build HP. A good flat BSFC curve allows more rpm without losing torque, which me potential for more HP. The is where the averages come in, peaks mean nothing. I will trade off 50 peak HP, for 1 more average HP. I launch my car at 4000 rpm and shift about 6500. RPM after than never drops below 3500, so anything lower than that is useless in a race, it only needs enough power below 3500 to pull it's ### to the starting line. The more average HP my car has from 3500-6500, the faster it is. Peak HP is about 6200, which doesn't matter, I'm only at 6200 RPM 4 times for a faction of a second. I'd trade off any amount of HP at 6200 to give me 1 more average HP between 3500-6500.

 

My gosh.... I'm scrambled I'm popping some more popcorn.